|
longitude: angle parallel to the equator to indicate position on the earth. The celestial longitude, however, is an angular distance parallel to the ecliptic.
|
lunar dial: dial where the shadow is cast by moonlight instead of sunlight, see article on the sundial.
|
lunar volvelle: volvelle indicating the age of the moon, which typically converts between the time indicated by the shadow of the moon on a sundial and solar time.
|
magic square: square grid with a number in each cell for which the sum of each row, column and diagonal is the same.
|
magnetic compass: instrument indicating directions by a magnetic needle, see article on the compass.
|
magnetic deviation: the angle between geographical north and the direction indicated by a compass needle.
|
magnitudes: numbers in a scale of the relative brightnesses of the stars, 1 being the brightest.
|
mariner's astrolabe: altitude-measuring instrument for finding latitude at sea, having a heavy brass or bronze ring, suspended by a shackle and ring, with a degree scale and a centrally-pivoted alidade.
|
mater: part of an astrolabe, see article on the astrolabe.
|
mathematical compendium: compound instrument for performing various functions in practical mathematics.
|
mathematical instruments: collections of instruments of assorted kinds for performing functions in practical mathematics.
|
measuring rod: an instrument used to measure distances or depths. See also gauging rod.
|
measuring rods: see measuring rod.
|
meridian: the plane containing the observer and both celestial poles, or containing the observer, the zenith and the pole, or, more colloquially, the north-south line at a particular position on the earth.
|
meridian circle: circular scale of degrees which in use is aligned with the meridian.
|
mining instruments: in this period mining instruments were principally for surveying, adapted for the special conditions of working underground in mines.
|
nautical circle: generic term for a circular mathematical instrument of use in navigation, but likely to carry a range of mathematical and astronomical scales.
|
nautical hemisphere: a combination of graduated arcs and circles used for navigational calculations, see article on the nautical hemisphere.
|
navicula dial: type of altitude dial in the shape of a ship.
|
nocturnal: instrument for finding the time at night from the orientation of the stars, see article on the nocturnal.
|